Belt drive



R. V. MORSE I May 7, 1940.

BELT DRIVE Filed Aug. 2, 1939 2 Sheets-Sheet 1 INVENTQR.

y 1940. R. v. MORSE 2.199.569

BEL T DRIVE Filed Aug. 2, 1939 I 2 Sheets-Sheet 2 INVENTOR.

Patented May 7, 1940 UNITED STATES PTENT OFFlC-E 4 Claims.

This invention relates to the transmission of power by V belts, with afixed ratio of rotation between the driving and driven shafts, as haspreviously been accomplished by chain drives or gears. Ordinary belts,whose contact with the pulleys was merely frictional, have heretoforebeen considered unsuited to drives where constant speed ratios wererequired, as any frictional belt has a tendency to creep. The generalprinciple underlying the present invention is the combination of avariable V belt drive which would normally creep, with a parallelregulatory drive of fixed ratio; the V belt drive carrying the heavyload, and the parallel control drive determining the ratio of both butcarrying only the light regulatory load,thus making possible the use ofV belts in fields previously monopolized by chains or gears, where theprecise transmission of fixed rotative ratios was the determiningfactor. 30 These basic principles are broadly covered in my copendingapplications Ser. No. 148,264, filed June 15, 1937, for Powertransmission, and the present invention relates to certain improvementsthereon, having for their objects simplification 25 of the mechanism,reduction in cost, and improvement in the ease of adjustment andassembly. A further object is to more satisfactorily drive the camshafts of engines. Various other objects will become apparent as thedescription proceeds.

Referring now to the drawings forming part of this specification, Fig. 1is an elevation partly in cross-section showing an improved form of theV belt pulley and regulatory mechanism.

Fig. 2 is a similar view of a modification.

Fig. 3 illustrates by way of example one typical application of suchmechanisms to a fixed ratio drive, in this case showing the V belt driveoperating the cam shaft, distributor, and other ele ments of an engine.

Similar reference numerals refer" to similar parts thruout the variousviews.

Referring now to Fig. 1, the shaft 1 has mounted thereon a variable Vbelt pulley 2 having a fixed pulley flange 3 secured to the shaft 1 by aset screw l or other suitable means. The flange 3 has a long hub 5, theend of which is threaded as at 6. The intermediate portion of the hub 5is smooth and has slidably mounted thereon the huh 'I carrying themovable V pulley flange 3. A feather key 9 between the hub 5 and the hubi compels the two flanges 3 and 8 to rotate in unison but allows the huhI and flange 8 to move axially relative to the flange 3, so as to varythe effective diameter of the V belt pulley 2. As the flanges 3 auditare drawn together the V belt I!) is caused to ride farther out on thepulley 2, and vice versa. The regulating mechanism for controlling thepitch of the pulley 2 operates thru the gear H which has a threaded borescrewing on the thread 6 of the hub 5. When the gear il turns in onedirection in relation to the thread 6 of the hub 5, it forces themovable flange 8 closer to the fixed flange 3, and increases theeffective pitch diameter of the pulley 2. When the gear H turns in. theopposite direction relative to the hub 5, it is withdrawn from the hub Iof the movable flange 8, but the wedging pressure of the v belt Illbetween the flanges of the pulley 2 forces the hub I to follow theretreating hub of the gear I I so as to always maintain contact. Theaction of the gear ll turning on the screw 6 thus varies the effectivediameter of the pulley 2 in either direction as desired. The collar 14provides an abutment against which the hub of the gear I i may look incase of extreme motion, and together with the collar It serves toposition the assembly relative to the bearing l6 if desired.

The regulating gear H is driven by gearing 20, or by any equivalentpositive mechanism such as the chain shown in my copending applicationabove mentioned, the drive to the gear H being so proportioned that itwill rotate the gear I l at precisely the rotational speed desired. Thepitch of the screw 6 is of such a direction that if the pulley 2 isturning slower than the gear H the gear H will screw to the left in Fig;1, followed by the hub 1 and pulley flange 8, separating the flanges 8and 3, and allowing the belt Hi to sink deeper in the pulley 2 androtating it at a higher speed. If the pulley speed exceeds that of thegear H, the reverse action occurs, the relative rotation of the gear Hon the screw 5 forces the flange 6 closer to the flange 3, and causesthe belt liitoassume a greater effective pitch diameteron the pulley 2,thus slowing down the rotation. of the-pulley 2. The result'is that thepulley seeks and maintains the same rotative speed as the control gearll In the form shown inFig. 1, the gear H travels axially in screwing onthe thread 6 of the hub 5, and accordingly it is generally desirable toprovide the meshing gear 20 with a wider face than the gear H, so thatit may fully engage at all points in its travel. When the regulating isdone with a chain drive this is not necessary,. as a chain is flexibleenough to allow for the slight lateral motion required.

The mechanism shown in Fig. 2 is in general similar to that shown inFig. 1, but differs in that the hub I of the movable flange 8 isthreaded so as to screw directly on a threaded hub 30 of the controllinggear II, and the pulley flange 3' does not have a threaded hub. In thiscase the control gear II is restrained against axial motion by the fixedcollar 3| and the bearing [6, so that the mating gear 20 of theregulating train does not need a wider face. The only lateral motion isin the flange 8' and its hub l, which travels laterally on the featherkey 9 as the screw 30 operates. This varies the effective diameter ofthe V belt pulley 2', so as to maintain a constant speed ratio in themanner described.

Fig. 3 illustrates the application of such devices to an internalcombustion. engine for'example, where they may be used to drive the camshaft and also the distributor if desired. The engine is designated bythe reference numeral 40 and is shown provided with a four cornereddrive in which the V belt Ill, driven by the pulley 4| on the crankshaft42, drives the pulley 43 of the generator 44, also the fan pulley l5,and the regulated variable pitch pulley 2", similar to the pulleys 2 and2 above described, which drives the cam shaft I, on which may also bemounted if desired the distributor 50. The regulating gear 20",corresponding to the gears 20 and 20 above described, is driven by thegear 5| mounted on the crank shaft 42. It will be noted that byemploying a train of three gears, the direction of rotation of the gearH, (which corresponds to the gears H and H above described), is in thesame direction as the belt driven pulley 2". The diameter of the gear H"is twice the diameter of the gear 5| in a four cycle engine, to give thetwo-to-one ratio desired for the cam shaft; and this ratio, being fixedby the regulating gearing, is automatically maintained by the V belt 1drive in the manner described.

While the gear train 5|, 20", and II" normally carries only the lightregulatory load, it may be designed if desired of sufficient strength sothat if the belt, which carries the main load, happens to break, thegears 5!, 20', ll may temporarily power from being used, while stillallowing the engine to run at reduced speed. This is accomplished byshifting the valve timing, and if desired the ignition timing, so as tomake the engine less eflicient. Referring to Fig. 1, it will be notedthat if the belt Ill should break the gear II would travel on the screw6 to the left until the hub of the gear ll locked against the collar l4,after which the parts would rotate as a unit. However, in so doing, thegear I I would have turned relative to the shaft I, so that the timingof the cam shaft l, and distributor 50 if attached thereto, would bethrown off considerably. This amount may be so proportioned that theengine can still run, but very slowly and inefficiently. The driver canthus be made aware of the failure of the belt but not otherwiseseriously inconvenienced. An advantage of such a drive is that belts canbe readily obtained and quickly installed at almost any gas station,Whereas the failure of an ordinary timing chain or gear is a seriousmatter requiring a major overhaul.

While I have in the foregoing described certain specific examples, itwill be understood that they are merely for purposes of illustration tomake clear the principles of the invention, which is not limited to theparticular forms shown, but is susceptible to various modifications andadaptations in different installations as will be apparent to thoseskilled in the art, without departing from the scope of the invention asstated in the following claims.

I claim:

1. In a V belt drive, the combination of a shaft, a V belt pulley flangesecured thereto, a second -V belt pulley flange movable axially relativeto the first mentioned flange so as to provide a V belt pulley ofvariable effective diameter, a V belt on said pulley, a threaded hub onthe first mentioned flange, a control wheel mounted on the threaded huband having a thrust face on the side toward the pulley, the secondmentioned flange having a thrust face bearing against the firstmentioned thrust face, said thrust faces being held in contact by thewedging pressure of the V belt between the pulley flanges, and means fordriving said control wheel at a fixed speed ratio, whereby the V beltdrive is maintained in synchronism with the ratio determined by thecontrol wheel drive.

2. In a V belt drive, the combination of a shaft, a V belt pulley flangesecured thereto, a second V belt pulley flange movable axially relativeto the first mentioned flange so as to provide a V belt pulley ofvariable effective diameter, a V belt on said pulley, an internallythreaded hub on the second mentioned flange, a control wheel mounted forrotation relative to said shaft and having an externally threaded hubmating with the internally threaded hub on the second flange so as toscrew the movable flange in either direction to vary the effectivediameter of the V belt pulley, thrust bearings for positioning thecontrol wheel, means for driving said control wheel at a fixed speedratio, whereby the V belt drive is maintained in synchronism with theratio determined by the control wheel drive.

In a V belt drive, the combination of a driving shaft, a driven shaft, amechanical control drive of fixed ratio between said shafts, a V beltdrive capable of variable ratio between said shafts, means forcontrolling the ratio of the V belt drive to maintain it in synchronismwith the mechanical control drive, the main load being carried by the Vbelt drive and the control drive carrying the regulatory load undernormal conditions, and means engaging the control drive to positivelycarry the main load thru the control drive in the event the V belt drivefails to function.

4. In a cam shaft drive, the combination of a crank shaft, a cam shaft,a V belt drive capable of variable ratio connecting the crank shaft andcam shaft, a mechanical drive of fixed ratio, regulating meanscontrolled by said mechanical drive to maintain the V belt drive at acorresponding fixed ratio, the main cam shaft load being carried by theV belt drive under normal conditions, means for locking the regulatorymechanical drive to the cam shaft in the event the V belt drive fails tofunction and simultaneously shifting the rotational setting of the camshaft so as to reduce the load on the cam shaft while it is being drivenby said regulatory drive.

ROBERT V. MORSE.

